Technical Field
The present subject matter relates to an onboard unit for levying toll for a vehicle, comprising a satellite navigation receiver for generating position fixes, a memory for recording geoobjects, a radio interface and a processor connected to these components, which is configured to generate toll data from a geographical comparison of position fixes with geoobjects in a digital map and to transmit this data via the radio interface. The present subject matter also relates to a method for updating geodata in such an onboard unit.
Background Art
Onboard units (OBUs) based on satellite navigation systems (global navigation satellite systems, GNSSs) usually use, as radio interface, a mobile radio module for terrestrial mobile radio networks (public land mobile networks, PLMNs) and are therefore also referred to as GNSS/PLMN OBUs. For the aforementioned geographical comparison (“map matching”) of the GNSS position fixes with the geoobjects stored in the OBU, it is necessary to quickly locate the closest geoobjects. To this end, a wide range of geographical or two-dimensional indices are currently used, such as quadtrees, R-trees or kd-trees and developments thereof, for example see Hanan Samet, “Foundations of Multidimensional and Metric Data Structures”, Morgan Kaufmann, 2006; M. deBerg et al., “Computational Geometry—Algorithms and Applications”, Springer, 1997; or Yannis Manolopoulos et al., “R-Trees: Theory & Applications”, Springer, 2006. Index trees of this type are optimised toward the data field to be searched (“balanced”) in order to minimise the average access time to the geoobjects arranged at the branch tips of the tree. Index trees and geoobjects are therefore coordinated with one another, which, for the updating of individual geoobjects, generally means that the index can also be recalculated. This requires either the transmission of greater data volumes via the radio interface, if the calculation is made centrally, or a higher computing power in the OBUs, if these perform the calculation decentrally, which in either case provides problems with the updating of geoobjects and indices thereof. The object of the disclosed subject matter is to create a solution to these problems.